From patchwork Fri Feb 2 22:04:57 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namhyung Kim X-Patchwork-Id: 13543508 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3978F132468; Fri, 2 Feb 2024 22:05:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706911510; cv=none; b=YcGUObPfeV4wFt26jI4TEDxkMkmeKDbvh9D4GeUZhwpu18muy7t8ewWyAGXOeyUcTyXurao639hB/3mujtKAru5eXRCwIUIBS9RE8Zcv+Jb9RHUQFs0PzViRku+9LncuLZL9Ut0WFjGpGsso5R8Hw/LbGNqj9ZPerQKhtY0QzNk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706911510; c=relaxed/simple; bh=ozKwyj+cawqB9+hDRoeS33gIgZE7kn/6L5uzLJ/tqHg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=h/FDJD6DonAnJ7PvYY8WHriLrdDxCGUhedy2chKIMiFKHMvAwyxg1bUE1qGG8satgBu2JyYO6Jo1DyGujUryzqAdupnm8cU8PjCj17wdPJNXokP7nlNmeYB23l1yLvtlby38CNwzVJOnksS+u7MH1x7IdbE4+6eIa4SPEe9Gspo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ejNmlryN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ejNmlryN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B67DAC433F1; Fri, 2 Feb 2024 22:05:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706911509; bh=ozKwyj+cawqB9+hDRoeS33gIgZE7kn/6L5uzLJ/tqHg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ejNmlryNPrqsqXEL0aqgztoVPSL1Y6D1cX/Y6sPy6aF8Yp3dfWyet1aTtRxwgBgyi gxv5vFbxXylNw6m1yi7nbtLbGTVMjMsib4ryT/3DnjUSf0xz/NNejb+4rgWW/49kSt NxCMdSH16x2zom61JG7hoZSvCGOe3ii9+QTgWe3TDMdckRQPxZDET71F8xcbY4RcrV ll6ORU5wjSSns4UCRG1ioFgZwl318nlSB7NaQFL1kzdw9xLGHRk+tSZ4W3ZohGgHev z7v5GZtVSSf6cWjXHFnGhNSgrhRRip7BArVFw+0uqfB87e317N3OmlvIb3+aGAITXw ml9RVjSKPpvOg== From: Namhyung Kim To: Arnaldo Carvalho de Melo , Ian Rogers Cc: Jiri Olsa , Adrian Hunter , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, Linus Torvalds , Stephane Eranian , Masami Hiramatsu , linux-toolchains@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH 12/14] perf annotate-data: Handle this-cpu variables in kernel Date: Fri, 2 Feb 2024 14:04:57 -0800 Message-ID: <20240202220459.527138-13-namhyung@kernel.org> X-Mailer: git-send-email 2.43.0.594.gd9cf4e227d-goog In-Reply-To: <20240202220459.527138-1-namhyung@kernel.org> References: <20240202220459.527138-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: linux-trace-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On x86, the kernel gets the current task using the current macro like below: #define current get_current() static __always_inline struct task_struct *get_current(void) { return this_cpu_read_stable(pcpu_hot.current_task); } So it returns the current_task field of struct pcpu_hot which is the first member. On my build, it's located at 0x32940. $ nm vmlinux | grep pcpu_hot 0000000000032940 D pcpu_hot And the current macro generates the instructions like below: mov %gs:0x32940, %rcx So the %gs segment register points to the beginning of the per-cpu region of this cpu and it points the variable with a constant. Let's update the instruction location info to have a segment register and handle %gs in kernel to look up a global variable. The new get_percpu_var_info() helper is to get information about the variable. Pretend it as a global variable by changing the register number to DWARF_REG_PC. Signed-off-by: Namhyung Kim --- tools/perf/util/annotate.c | 31 +++++++++++++++++++++++++++++++ tools/perf/util/annotate.h | 4 ++++ 2 files changed, 35 insertions(+) diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c index 86ac44c476bf..5f3136f57c62 100644 --- a/tools/perf/util/annotate.c +++ b/tools/perf/util/annotate.c @@ -3810,6 +3810,27 @@ void get_global_var_info(struct thread *thread, struct map_symbol *ms, u64 ip, addr_location__exit(&al); } +void get_percpu_var_info(struct thread *thread, struct map_symbol *ms, + u8 cpumode, u64 var_addr, const char **var_name, + int *poffset) +{ + struct addr_location al; + struct symbol *var; + u64 map_addr; + + /* Kernel symbols might be relocated */ + map_addr = var_addr + map__reloc(ms->map); + + addr_location__init(&al); + var = thread__find_symbol_fb(thread, cpumode, map_addr, &al); + if (var) { + *var_name = var->name; + /* Calculate type offset from the start of variable */ + *poffset = map_addr - map__unmap_ip(al.map, var->start); + } + addr_location__exit(&al); +} + /** * hist_entry__get_data_type - find data type for given hist entry * @he: hist entry @@ -3906,6 +3927,16 @@ struct annotated_data_type *hist_entry__get_data_type(struct hist_entry *he) &dloc.type_offset); } + /* This CPU access in kernel - pretend PC-relative addressing */ + if (op_loc->reg1 < 0 && map__dso(ms->map)->kernel && + arch__is(arch, "x86") && op_loc->segment == INSN_SEG_X86_GS) { + dloc.var_addr = op_loc->offset; + get_percpu_var_info(he->thread, ms, he->cpumode, + dloc.var_addr, &dloc.var_name, + &dloc.type_offset); + op_loc->reg1 = DWARF_REG_PC; + } + mem_type = find_data_type(&dloc); if (mem_type) istat->good++; diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h index 2bd654620de3..490134d19c9d 100644 --- a/tools/perf/util/annotate.h +++ b/tools/perf/util/annotate.h @@ -513,6 +513,10 @@ void get_global_var_info(struct thread *thread, struct map_symbol *ms, u64 ip, struct disasm_line *dl, u8 cpumode, u64 *var_addr, const char **var_name, int *poffset); +void get_percpu_var_info(struct thread *thread, struct map_symbol *ms, + u8 cpumode, u64 var_addr, const char **var_name, + int *poffset); + /** * struct annotated_basic_block - Basic block of instructions * @list: List node